DEVELOPMENT AND IMPLEMENTATION OF AN INSTRUMENTED FAILING DRILL FOR THE PREDETERMINATION OF PILE BEARING CAPACITY

The investigation involved the development and modification of an instrumentation system for the Failing drill for the measurement of the translatory motion of the drill rod during driving, with subsequent data acquisition at selected field sites; and, the development of improved data interpretation procedures on the basis of the static and dynamic features of the drill-rod/soil interaction, with subsequent application to the acquired field data. As a consequence of the high inertial forces of the hammer-drill rod impact for the Failing drill, the lead-wire/attachment arrangement and possibly the motion sensor itself are susceptible to damage during driving. However, the application of a velocity meter for monitoring full-scale pile motion should yield useful information and involve minimal inconvenience when utilized. Procedures for the conversion and interpretation of field data, involving a data transfer from a magnetic tape unit to a PDR-8E computer via analog to digital convertors, were successfully developed and tested. As regards the actual data interpretation procedures, the use of a dynamic rigid-pile model based on hammer-energy/pile-motion considerations is not advisable due to the lack of rigidity of the Failing drill system; however, the application of this theory to full-scale pile driving appears to hold considerably more promise. A dynamic elastic-pile model, based on one-dimensional wave motion principles, yielded quantitatively acceptable information for blow count and associated bearing capacity (drill-rod pull-out load) of the Failing drill rod. Finally, a static rigid-pile model, formulated on the basis of the psuedoplastic of soil, was utilized in conjunction with field data to determine a coefficient of sliding friction at the pile-soil interface of 0.12 to 0.17, and a zone-of-influence around a driven pile of two to six pile diameters for typical field soils.

  • Corporate Authors:

    South Dakota Department of Transportation

    Division of Highways, Foundation and Geology Program
    Pierre, SD  United States  57501
  • Authors:
    • Bump, V L
    • Krause, K E
    • Huft, David L
    • Gnirk, P F
  • Publication Date: 1975-1

Media Info

  • Pagination: 76 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00126502
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: 605 (72) Final Rpt.
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Jan 14 1976 12:00AM